Although many details concerning the attacks that killed more than 120 people in Paris on Friday night remain unknown, Islamic State appears to have claimed responsibility. France and all other countries taking part in the Syrian conflict should keep in mind Russia's recent experience with this kind of terrorism: It won't cease until the epicenter is dealt with.

French President Francois Hollande said on Saturday morning that the attacks were "an act of war" carried out by a jihadist "army." That may be true in a sense, even if it turns out that some of the attackers were untrained or French residents or citizens (eyewitnesses of the who saw attackers fire randomly into the crowd at the Bataclan concert venue said they spoke French without a foreign accent).

Four of the eight known attackers -- three in the vicinity of Stade de France, where the French soccer team was playing Germany, and one on Boulevard Voltaire -- blew themselves up without causing any major damage. Only one civilian casualty was attributed to these botched attacks.

The other terrorists took more than 120 lives, simultaneously shooting into the audience at Bataclan and at patrons of a busy cafe. This synchronization maximized the terror effect not so long after the Charlie Hebdo terror attacks in January, which killed 17. This is a pattern all too familiar to Russians.

In 2004, a series of terror attacks shook the country. The second Chechen war between Russian security forces and separatist guerrillas in the Caucasus had been underway for almost five years when a suicide bomber blew up a subway train in Moscow in February of 2004, killing 42 people. In June, 10 people were killed by a bomb in a crowded market in the provincial city of Samara; soon afterward, police offices in the Caucasus republic of Ingushetia were attacked with hundreds of casualties. In August, kamikazes blew up two passenger airliners, claiming 90 victims, and another suicide bomber detonated herself near a subway station, taking 10 lives (it would have been more if she had managed to go down into the subway, but she was stopped by a vigilant cop).

Finally, in early September, a Chechen band seized 1,128 hostages at a school in Beslan, North Ossetia; 334 civilians, including 186 children, died during the three-day siege. It ended when special forces stormed the building and killed 31 terrorists.

Russia has seen more terrorist attacks since that horrible year, but never another series on that scale. In 2005, President Vladimir Putin recruited the son of Chechnya's former top Muslim cleric, Akhmad Kadyrov -- killed in yet another 2004 terror attack -- to run Chechnya for him. Ramzan Kadyrov, then 29, was eager to avenge his father's death, and since the Kadyrovs had once been separatists themselves, he had an excellent intelligence network in the war-torn region.

Kadyrov got from Putin generous funding and a dispensation to ignore federal laws, sparing no one he considered an enemy. It took him a little more than three years to end the war and make it pointless for the defeated separatists to plot terror attacks on Russian cities. The campaign was, to use the word Hollande employed in the context of Islamic State, "pitiless." The few big attacks that followed were only an echo of a once-powerful campaign.

In 2004, the main war was being fought in the mountains of Chechnya and attacks on Moscow and other peaceful cities were a way for Islamist rebels to instill fear into ordinary Russians, raising the cost of war for the government.

The Paris terrorists may have the same motivation. The main war today is being fought in Syria. Islamic State claimed responsibility on Saturday, as it did for suicide attacks in Beirut on Thursday that killed at least 43 people. It appears increasingly likely that Islamic State may have blown up a Russian plane over Egypt last month, killing 224, in retribution for Russia's bombing campaign in Syria. Now the group also appears to have taken revenge on the French, which extended its air strikes against Islamic State from Iraq to Syria in September. On Nov. 5, France said it was sending an aircraft carrier into the Mediterranean to support the effort. Like the Chechen terrorists in 2004, Islamic State terrorists are trying to make military action against their stronghold costly for the powers involved.

France has not ignored domestic security since the Charlie Hebdo attack. It increased its terrorist-fighting cadre by more than 2,500 people. Intelligence services are constantly watching the estimated 1,500 people who have fought for jihadis in Syria and Iraq, and they now have a catalog of 11,000 more people they consider dangerous radicals. Barriers to broad and constant surveillance are falling. A new intelligence law, drafted after the Charlie attacks, now allows the prime minister to authorize real-time monitoring of electronic communications, physical surveillance and the bugging of homes to preempt terrorist threats -- all without court orders.

France has also been accepting relatively few Syrian refugees, making it unnecessary for intelligence services to check hundreds of thousands of people for terrorist connections.

None of these measures, however, will prevent further attacks, just as Putin's mighty, unaccountable law-enforcement agencies could not stop the horror of 2004. They, too, had catalogues of suspects and almost unlimited powers to watch and listen. Sometimes they managed to stay a few steps ahead, but it's an endeavor that cannot be 100-percent successful. Islamist groups are good at attracting new recruits and it doesn't take long to arrange a shooting or a suicide bombing.

Putin intervened in Syria in part because he remembers Chechnya, and because thousands of the separatists who fought him there have now joined the ranks of Islamic State and al-Qaeda's Syrian franchise, the al-Nusra Front. These people represent a threat like the one Russia faced in 2004, because a new war provides a new goal and new sources of funding.

Putin's bet is now the same as in Chechnya: He aids a ruthless local leader, Bashar al-Assad, in taking the war to anyone who takes up arms, whether an Islamist, a terrorist or a separatist.

France and other U.S.-led coalition countries must all now assume they are potential targets for attacks like the ones in Paris. They need to decide whether they should subscribe to Putin's method of stamping out terror. It proved effective in Chechnya, though not even he can know whether it would work in Syria. One thing is clear, though: Until the Syrian conflict is resolved and Islamic State is defeated at its epicenter, no country is safe from attacks like the one that shook Paris on Friday night.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.